They swarmed in their thousands across the distinctive "rusty" Corten steel bridge to sample the new shopping experience at what is being trumpeted as "where east meets Westfield".

In the autumn sunshine came large family groups with buggies, twentysomething female shoppers, teenagers skipping school and octogenarians curious to see what all the fuss was about.

Although the shops did not officially open until 10am, by 7.30am hundreds were queueing up at the end of the bridge that provides the main public entrance to Westfield Stratford, waiting for the main doors to open at 8am.

The £1.4bn shopping centre, gateway to the Olympic site in Stratford, east London, has more than 300 shops, 70 restaurants, a 14-screen cinema, three hotels, a 14-lane bowling alley and the UK's largest casino.

Early birds at the centre, the largest urban complex in Europe, were on a mission, causing a minor stampede as they made a beeline for Forever 21: the American clothing chain was offering £50 vouchers and goodie bags to the first shoppers in the queue outside only its second branch in the UK after Oxford Street.

At the official opening of the centre there was embarrassment as a glass ceiling tile smashed close to the London mayor Boris Johnson. The tile dropped near a stage where pop star Nicole Scherzinger had just performed live as part of the star-studded ceremony. The large glass tile – roughly 5ft by 2.5ft – dropped 30ft to the ground near the HMV store, shattering on impact.

Johnson, who had been giving a radio interview at the time, brushed off the incident saying: "They have worked flat out down here and whatever has happened over there [where the roof tile fell], I'm sure will be investigated and cleared up as soon as possible."

In pole position in the Forever 21 queue was Winnie Wechie, a medical student from Deptford in south-east London about to return to Aberdeen University, who planned to swap her voucher for some "nice warm knitwear". She was upbeat about the complex: "The range of shops is diverse but it's all under one roof. I usually shop in Lewisham or Oxford Street but this is all amazing. I will be back."

The complex is teardrop-shaped, with three floors of shops and landscaped outdoor walkways and terraces. Some 70% of visitors to the stadium and park will be funnelled straight through Westfield – meaning their first taste of the Olympic experience will be a giant Marks & Spencer sign, red Westfield branding and a neverending avenue of shops.

John McDermott, 21, who lives in Buckhurst Hill, Essex, and works in media sales was heading for designer brands like Superdry. Bleary-eyed after being woken by his girlfriend at 4.45am to get to Stratford early, he said: "I didn't get any Olympic tickets so it will be great to come back when the games start and watch some of the events on the big screens."

Students were out in force, keen to snap up bargain bedding and other essentials for the start of the new academic year. Some were disappointed that some major retailers, including H&M and Vodafone, were not yet open.

Some locals were concerned about the future of retail in the area. Aisha Khan, 19, who lives in Stratford, said: "I really think the local shopping centre is going to suffer from this. I'm not sure they realise what a massive impact it is going to have."

Others felt it might force local retailers to raise their game. Yolanda Akinti, 18, also from Stratford, was visiting with two friends. She said: "This is so much better than the local mall, which is absolutely dreadful. I think the supermarkets there like Sainsbury's and Morrisons will continue to do OK, but why would you go to the dump of a cinema when you could come to the new [14-screen] Vue here?"

From further afield were Sharron Vincent, from Knutsford in Cheshire, and her daughter Tamsin, a drama student at Queen Mary College in nearby Mile End, who were looking forward to a leisurely day. Mrs Vincent said: "I shop at the Trafford Centre but this seems so much nicer and cleaner. It is very stylish with a great selection of shops. We have no particular plans. We are here to shop, eat and drink."

By 11am the shopping experience had already proved too much for some visitors, who succumbed to the temptation of a glass of Marquis de Marillac champagne (£8.50) at Searcys Champagne Bar.

Elsewhere West Ham boss Sam Allardyce and some of his star players helped launch the club's new official shop. Weighed down with bags from the store was Vida Baker, with her young sons George and Matthew. Her mother-in-law Georgina Baker, from Plaistow, gave the centre the thumbs-up. "It's a short hop on the bus from home," she said. "At the moment I go to Lakeside in Thurrock but in the future I will come here. The only thing I am worried about is the cost of parking, as if you are doing a large shop you don't want to lug it all home on the bus. And I would have liked a Debenhams."

The new, £40m John Lewis is the only full department store on the site, after the retailer became first to commit to Westfield. Managing director Andy Street said he was "very proud" to have created more than 800 new jobs at the new branch, with a large proportion going to local people who have been unemployed for a long time or have never worked.

As the centre opened there was a sizeable police presence, particularly around Stratford station. But Sir Robin Wales, mayor of Newham, was keen to emphasis that Westfield will be there long after the athletes have packed up their tracksuits and gone home. He said: "Shoppers, tourists and visitors will also bring further economic benefits to Newham and will leave a lasting legacy long after the Olympics has rolled out of town."